U.S. patent number 7,690,205 [Application Number 11/231,949] was granted by the patent office on 2010-04-06 for gas turbine engine cold start mechanization.
This patent grant is currently assigned to Honeywell International Inc.. Invention is credited to Jim E. Delaloye, Joe Keck, Barry J. Kingery.
United States Patent |
7,690,205 |
Delaloye , et al. |
April 6, 2010 |
Gas turbine engine cold start mechanization
Abstract
An apparatus and method is provided to start gas turbine engines
at cold start. A gearbox is not mechanically coupled to any
accessory or to the starter-generator. Rather, a controller is used
to route power to a starter-generator to rotate the turbine
mainshaft to start the gas turbine engine. The controller prevents
power to an accessory drive motor, until the starter-generator
creates a positive torque. When a positive torque is reached,
excess power is routed to the accessory drive motor, typically a
brushless direct current motor.
Inventors: |
Delaloye; Jim E. (Chandler,
AZ), Keck; Joe (Gilbert, AZ), Kingery; Barry J.
(Glendale, AZ) |
Assignee: |
Honeywell International Inc.
(Morristown, NJ)
|
Family
ID: |
38573659 |
Appl.
No.: |
11/231,949 |
Filed: |
September 20, 2005 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20070234739 A1 |
Oct 11, 2007 |
|
Current U.S.
Class: |
60/786;
60/788 |
Current CPC
Class: |
F01D
19/00 (20130101); F02C 7/275 (20130101); F05D
2260/85 (20130101); F05D 2260/40 (20130101) |
Current International
Class: |
F02C
7/26 (20060101); F02C 7/275 (20060101) |
Field of
Search: |
;60/802,786,39.13,787,788,734,39.281 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cuff; Michael
Assistant Examiner: Sung; Gerald L
Attorney, Agent or Firm: Ingrassia Fisher & Lorenz,
P.C.
Government Interests
GOVERNMENT RIGHTS
This invention was made with Government support under Contract no.
N0001902C3002 awarded by the United States Government. The
Government has certain rights in this invention.
Claims
We claim:
1. A turbine engine control system, comprising: a starter/pump
controller configured to send power to a starter-generator, said
starter/pump controller configured to prevent power from being
directed to an accessory drive motor if said starter-generator is
operating with negative torque; and a bulk oil temperature sensor
configured to initiate a start sequence for said starter/pump
controller if the bulk oil temperature is less than a
pre-determined threshold value.
2. A turbine engine control system of claim 1, wherein said
starter-generator is operably connected in parallel with said
accessory drive motor.
3. A turbine engine control system of claim 1, wherein said
accessory drive motor is a brushless direct current motor.
4. A turbine engine control system of claim 1, wherein said bulk
oil temperature sensor is configured to route power to an accessory
drive motor and to said starter-generator regardless of said
staffer-generator torque.
5. A turbine engine control system of claim 1, wherein said
accessory drive motor is a lubricant pump drive motor.
6. A turbine engine control system of claim 1, wherein said
starter/pump controller is further configured to prevent lubricant
from being displaced from a lubricant pump while said
staffer-generator is operating with a negative torque.
7. A turbine engine control system of claim 1, wherein said
starter/pump controller is further configured to enable lubricant
to be displaced while said starter-generator is operating with a
net positive torque.
8. A turbine engine control system of claim 1, further comprising a
sensor operably connected to route power to the accessory drive
motor if said starter-generator is operating with non-negative net
torque.
9. A turbine engine control system of claim 1, further comprising a
sensor operably connected to route power to the accessory drive
motor if said starter-generator is operating with net positive
torque.
10. A turbine engine control system of claim 1, further comprising
a sensor operably connected to route power to a turbine engine if
said starter-generator is operating at a net negative torque.
11. A turbine engine control system of claim 1, further comprising
computer readable media operably connected to at least one
sensor-controller or said starter/pump controller.
12. A gas turbine engine cold start system, comprising: a bulk oil
temperature sensor configured to trigger a starter/pump controller
to initiate a cold start procedure if the bulk oil temperature is
less than a pre-determined threshold temperature; and a
starter/pump controller configured to govern power to a
starter-generator and configured to govern power directed to an
accessory drive motor if said starter-generator is operating with
negative torque.
13. The gas turbine cold start system of claim 12, wherein said
accessory drive motor is a fuel pump motor.
14. The gas turbine cold start system of claim 12, wherein said
accessory drive motor is a lubricant power drive motor.
15. The gas turbine cold start system of claim 13, wherein an
electric current through the fuel pump motor is determined by the
fuel pump motor speed.
16. The gas turbine cold start system of claim 12, wherein an
electric current through said starter-generator is determined by
the torque demanded by the starter-generator.
17. The gas turbine cold start system of claim 14, wherein an
electric current flowing through the lubricant power drive motor is
determined by the pressure demand of the lubricant power drive
motor.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a start up mechanization
for gas turbine engines. Particularly, the present invention
relates to an apparatus for the cold starting of a gas turbine
engine using a controller and direct current motor, rather than a
gearbox.
U.S. Pat. No. 3,769,790 discloses a means to prohibit flow of
lubricating oil to the engine by a valve that is energized to dump
the lubricating oil driven by the pump driven by the engine, column
1, lines 58-64. The '790 patent employs a gearbox, referred to as a
reduction gear arrangement or transmission 18, in the single Figure
of the '790 patent. This patent requires the use of a gearbox.
U.S. Pat. No. 6,732,529 discloses a clutch that disengages
accessories to avoid delivery of excess fuel and oil into the
engine during start-up. However, the disclosed clutch mechanism is
limited for use with gearboxes, as described in column 3, lines 5-8
of the '529 patent. The gearbox is illustrated in FIG. 3 of the
'529 patent. This patent also requires the use of a gearbox.
Aerospace grade gas turbine engine start power is limited by the
size of the energy source, e.g., battery, because energy has to be
directed to start the turbine engine, and also to an accessory such
as a lubricant pump drive motor to pump lubricant or oil. The
battery size can be reduced if less power is required, or, if the
distribution of power can be used more efficiently. Therefore,
start up mechanization is critical in creating a design, which
results in minimum stored energy source, e.g. battery size.
Conventionally, accessories for gas turbine engines can be divided
into two categories; those driven by bleed air taken from the
compressor section of the engine, and those driven mechanically by
an accessory drive shaft and gearbox connected directly to the
turbine shaft. The mechanical connection from the turbine shaft may
be through an engine-mounted gearbox or through a power takeoff
shaft to a remotely mounted gearbox.
Accessories driven by bleed air operate by utilizing high-pressure
air that is available for driving aircraft accessories by air
motors or air turbines. Compressor discharge air at high pressure
and temperature is bled from the engine through ports. This air is
ducted as a source of power. It operates accessories such as the
air-conditioning units, hydraulic pumps, thrust reverser actuators,
and various mechanical actuators in the airplane. Air for cockpit
or cabin pressurization is also provided by bleed air from the
engine compressor.
On multi-engined aircraft equipped with pneumatic engine starters,
one engine is usually started from an auxiliary power unit or a
ground air source. Air from this operating engine is bled through a
system of ducts in the aircraft to power the starters of the other
engines.
Use of an accessory drive gearbox (AGB) is a second method of
driving accessories. This apparatus is a direct mechanical drive
that is operated by gearing from the compressor-turbine drive
shaft. Accessory drives and accessory mounting pads are provided in
an engine-mounted, accessory drive gearbox or in a remotely mounted
gearbox. On some turbojet engines, accessory pads and mechanically
powered drives are also provided in the engine nose section. For
dual compressor, axial-flow engines, the main accessory drive
gearbox usually receives its power from the high-pressure
compressor drive shaft. Mechanically driven accessories may include
tachometers, generators or alternators, hydraulic pumps, fuel
pumps, oil pumps (also known as lubricant pump drive motors), fuel
controls, starters, and water pumps. In the case of AGB-driven
accessories, a starter-generator is mechanically coupled to the
compressor-turbine drive shaft to rotate the compressor-turbine
drive shaft. The compressor-turbine drive shaft, or compressor
shaft, is drivably coupled to accessories, such as a fuel pump and
a lubricant pump drive motor (LPDM).
A conventional gearbox requires energy from the battery source to
drive components, which include gears, shafts, and clutches.
Typically, a bevel gear is located at the front end of the
compressor shaft; the bevel gear meshes with a planetary gear
train, which may be housed in an inlet housing. This planetary gear
train transmits low-pressure compressor power through two drive
shafts: one to the starter gearbox, the other to the accessory
gearbox to drive an idler system. A gear located on an output power
shaft interconnects with a 90.degree. pinion gear in the output
power shaft support housing. The gears drive the high-pressure
section of an accessory gear train.
The gear arrangement of the gearbox that causes energy draw
typically includes the bevel gear, being the accessory gearbox
drive gear, which is splined internally to accept the accessory
gearbox shaft. This drive shaft connects the gear carrier to the
accessory gearbox through the 900 pinion gear, which in turn is
splined directly to a starter-generator drive gear. The
starter-generator drive gear provides drive to all subordinate
gears located within the accessory gearbox housing.
The energy required to start the engine, or rotate the compressor,
must be in excess of that required to overcome rotor inertia and
engine friction and air loads. The starter must produce sufficient
torque to start the engine properly. Engines must be rotated and
accelerated above a certain minimum rotational and acceleration
rates if consistently good starts are to be achieved. The torque
characteristics of an acceptable starter must be well above the
required minimum.
FIG. 1 is a schematic of a start control scheme according to the
prior art. A battery 10 provides power to a full authority digital
electronic controller (FADEC) 12, which is operably connected to a
starter controller and/or pump controller 14. FIG. 1 shows the
starter/pump controller 14 as one integrated controller. However,
in some prior art systems, the starter controller may be physically
separated from the pump controller. The starter/pump controller 14
is operably connected to a starter generator 16 and a lubricant
pump drive motor 18.
As can be gathered from the foregoing background, the accessory
gearbox with its many components is heavy and large. Further, the
gearbox requires energy to drive the gears, components, and
accessories.
Therefore, there is a need for a cold start mechanization that
reduces weight, occupies less space, requires less energy, and
minimizes stored energy source size.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided
a turbine engine control system comprising a starter/pump
controller configured to send power to a starter-generator, said
starter/pump controller configured to prevent power from being
directed to an accessory drive motor if said starter-generator is
operating with negative torque; and a bulk oil temperature sensor
configured to initiate said starter/pump controller if the bulk oil
temperature is less than a pre-determined threshold value.
According to another aspect of the present invention, there is
provided a gas turbine engine cold start mechanization, comprising
a full authority digital electronic controller, said full authority
digital electronic controller operably connected to at least one of
a turbomachine supply system oil pressure sensor, or an oil
temperature sensor, or a rotor position sensor, whereby based on
the sensed oil pressure, oil temperature, rotor position, or rotor
speed, said full authority digital electronic controller is
selectively able to route power to a starter-generator or an
accessory drive motor.
According to yet another aspect a gas turbine engine cold start
system of the present invention comprises a bulk oil temperature
sensor configured to initiate a starter/pump controller if the bulk
oil temperature is less than a pre-determined threshold
temperature; and a starter/pump controller configured to govern the
power to a starter-generator and configured to govern the power
directed to an accessory drive motor if said starter-generator is
operating with negative torque.
These and other features, aspects and advantages of the present
invention will become better understood with reference to the
following drawings, description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a start control scheme of the prior art;
FIG. 2 is a schematic block diagram of a start control system of
the present invention;
FIG. 3 is a graph illustrating a lubrication pump drive motor power
or current profile of the present invention;
FIG. 4 is a schematic diagram of current flow paths for the
accessory motors of a gas turbine engine start control system of
the present invention;
FIG. 5 is a block diagram of a method for controlling a cold start
of a gas turbine engine according to another embodiment of the
present invention;
FIG. 6 is a block diagram of an exemplary embodiment of how the
present invention may interact with computer readable media;
FIG. 7 is a block diagram of a further embodiment of the present
invention operably connected to a full authority digital electronic
controller (FADEC); and
FIG. 8 is a block diagram of a further embodiment of the present
invention used with a rotor or shaft position sensor.
DETAILED DESCRIPTION OF THE INVENTION
The following detailed description is of the best currently
contemplated modes of carrying out the invention. The description
is not to be taken in a limiting sense, but is made merely for the
purpose of illustrating the general principles of the invention,
since the scope of the invention is best defined by the appended
claims.
Broadly, the present invention provides apparatus and methods for a
cold start of a turbine engine without the use of a gearbox.
Instead of a gearbox, the present invention uses a controller and a
motor to take over certain functions formerly performed by the
gearbox. The present invention can be manufactured as a component
of newly assembled gas turbine engines, or it can be retrofitted
into existing gas turbine engines. The invention may employ
controllers and brushless motors to divert power to the
starter-generator, until the starter-generator creates positive
torque, at which time a controller can route power to the brushless
motors to drive a respective accessory.
In the present invention, the electric motor driven hydraulic pump
assembly is not mechanically coupled to the gearbox. A digital
controller can control the hydraulic pump or drive motor speed as
well as actuation of an electromechanical valve to delay the start
time at which the pump assembly consumes power. The digital
controller of the present invention employs brushless direct
current (DC) motors to drive units such as a lubricant pump drive
motor, that in prior art systems are drivable by a gearbox.
Therefore stored power, such as from a battery, can be delivered to
the gas turbine until the gas generator produces a net positive
torque. When the gas generator produces a net positive torque,
caused by the starter-generator, the excess electrical power can
then be routed to the hydraulic pump drive motor.
Structurally, the present invention differs from the prior art by
not having a gearbox to drive accessories. Instead of a gearbox, an
accessory can be driven by a brushless direct current motor, which
can be controlled by a controller.
FIG. 2 is a schematic block diagram of a start control system 99 of
the present invention. An energy source 100, such as a battery, can
provide power for a controller, such as a sensor-controller 110.
The sensor-controller 110 may receive power from the energy source
100. A sensor-controller 110, also referred to herein as a bulk oil
temperature sensor or a lubrication supply system pressure sensor,
can sense bulk oil temperature or lubrication supply system
pressure, among other properties (also see FIG. 7). The bulk oil
may be within an engine reservoir (not shown). If the bulk oil
temperature is below a certain temperature, such as a
pre-determined threshold temperature; or if the lubrication supply
system pressure is below a certain pressure, such as a
pre-determined threshold pressure, then the sensor-controller 110
may initiate a cold start sequence.
As a non-limiting example, the pre-determined threshold temperature
may be about -40.degree. C. (-40.degree. F.). Although FIG. 2
identifies the sensor-controller 110 as the device that senses bulk
oil temperature, other sensing devices may work, and need not be
physically part of the sensor-controller 110. If the bulk oil
temperature is above the threshold temperature; or if the
lubrication supply system pressure is above the threshold pressure,
then the present invention may not need to be utilized.
If a sensor device, such as the sensor-controller 110, senses that
the bulk oil is below the pre-determined threshold temperature; or
if the lubrication supply system pressure is above the threshold
pressure, the cold start sequence may be initiated by the
sensor-controller 110 electronically signaling a starter/pump
controller 120 of the present invention. The starter/pump
controller 120 may include a FADEC 122. In other words, in an
exemplary embodiment of the invention, the starter/pump controller
120 may be interchangeable with a FADEC 122. The starter/pump
controller 120 may govern or prioritize the routing of electrical
power, and may route power to, and activate, the starter-generator
130. Simultaneously the starter/pump controller 120 may be
selectively able to divert power to the starter-generator 130 from
an accessory, such as a lubricant pump drive motor (LPDM) 160,
which may drive a lubricant pump 170. The starter-generator 130 may
be drivably connected to rotate the gas turbine engine rotor 140 to
start the gas turbine engine 145. Further, the bulk oil temperature
sensor may be configured to route power to an accessory drive
motor, such as a LPDM 160 and to the starter-generator 130
regardless of the starter-generator torque. Although a lubricant
pump 170 is referenced, the system may drive any suitable pump
170.
In one exemplary embodiment, the lubricant pump drive motor 160 may
be a brushless direct current (DC) motor, as schematically
diagramed in FIG. 4. Further, an additional accessory of the start
control system 99 of the present invention may comprise a fuel pump
(not shown), which may be driven by a fuel pump drive motor 180, as
seen in FIG. 4. The starter-generator 130 may be electronically
connected in parallel with the lubricant pump drive motor (LPDM)
160 or a fuel pump drive motor 180.
Once again referring to FIG. 2, a sensor 150 can determine whether
the starter-generator 130 is producing negative net torque.
"Negative net torque" is defined as the starter-generator 130 not
providing enough power to the gas turbine engine for the gas
turbine engine to be self-sustaining. Conversely, "positive net
torque" is defined as power that is produced by the gas turbine
engine rotor in excess of that required to overcome rotor inertia
and engine and friction air loads.
If the starter-generator 130 produces negative net torque, then the
starter/pump controller 120 can continue to route power to the
starter-generator 130, diverting power from an accessory motor,
such as the LPDM 160. In addition to the routing or diverting of
power, if the starter-generator 130 produces negative net torque,
an electromechanical valve 175 may be actuated to prevent the LPDM
160 from displacing lubricant fluid from the lubricant pump 170
within the gas turbine engine rotor 140.
Once the starter-generator 130 produces positive net torque, power
may be generated by the starter-generator 130. Alternatively, once
the starter-generator 130 produces a non-negative net torque, power
may be generated by the starter-generator 130. This power, referred
to as excess power, can then be directed to the accessory motor
160, such as the LPDM 160 or the fuel pump drive motor 180. The
term accessory motor 160 and LPDM 160 may be used interchangeably
because the system may power any suitable motor 160. Accordingly,
when the starter-generator 130 produces positive net torque, the
electromechanical valve 175 may be closed to cause lubricant to
move to the gas turbine engine to cool and lubricate the
engine.
Although FIG. 2 depicts the sensor-controller 110 and the
starter/pump controller 120 as being physically separate, they may
be integrated into one single integrated controller 190, as shown
by the dashed line of FIG. 2.
FIG. 3 illustrates an exemplary cold start profile for a start
control system of the present invention. Specifically, FIG. 3 is a
graph that illustrates the relationship of percentage of main
shaft, or rotor 140 speed on the x-axis, with respect to power or
current usage by an accessory on the y-axis, during a typical cold
start event for a gas turbine engine according to an embodiment of
the present invention.
Percentage values below the x-axis of FIG. 3 refer to percentage of
turbine engine main shaft speed. Starting at the origin and
proceeding rightwardly along the x-axis (prior to reaching 430,
which is the minimum percentage of main shaft speed to attain self
sustaining power). The starter/pump controller 120 or FADEC 122 may
direct wattage to be applied to the accessory, and may also
initiate rotation of the LPDM 160. Also, the electromechanical
fluid control valve 175 can be opened at this point.
As further illustrated in FIG. 3, after reaching the self
sustaining point 430, excess power or current produced by the
starter generator item 130 may be delivered to the LPDM 160. In one
exemplary embodiment, about 500-600 watts may initiate pump shaft
rotation at cold start, e.g., at a temperature of about -40.degree.
C. (-40.degree. F.). As the mainshaft rotor 140 is rotating at cold
start, the delivered wattage may be maintained at about 600 watts
to initiate lubricant pump shaft rotation prioritizing power to the
starter generator item 130. Then, after the mainshaft has rotated
whereby the inertia required to start the electromechanical valve
175 may be decreased, the wattage can be decreased slightly, to
close the electromechanical valve 175, if opened, as denoted by
line 440.
Again with reference to FIG. 3, when the self sustaining speed 430
is reached, the starter generator 130 may be cut-out, or turned
off, by the starter/pump controller 120 or the FADEC 122. At this
point, the starter-pump controller 120 may send about 2500-3000
watts to the LPDM 160 for about 30 seconds, as an example. Starting
at, for example, 70% of rotor 140 speed, excess power that is
generated by the starter-generator 130 may now be available for use
by the accessories, or the accessory motors, such as the LPDM
160.
At about 100%+5 seconds of mainshaft speed, for example, the
starter/pump controller 120 may reduce the power input to some
reduced level as cooling oil flow is now routed through the
machine.
FIG. 4 illustrates exemplary current flow paths from a battery buss
200 through at least one insulated gate bipolar transistor (IGBT)
135, 185, 165 for the starter-generator 130, the fuel pump drive
motor 185, or the LPDM 160 of the present invention; the flow path
continuing from each of the starter-generator IGBT 135, the fuel
system drive motor 185, and the LPDM 165 to a return 210. The
respective IGBT 135, 185, or 165 can turn the respective
starter-generator 130, fuel pump drive motor 180, or LPDM 160 on,
if the current or voltage exceeds a certain pre-determined
value.
With reference to FIG. 4, in a further exemplary embodiment of the
present invention, the electric current delivered to the fuel pump
motor 180 may be determined by the required/scheduled fuel pump
drive motor 180 speed, the current through the starter-generator
130 may be determined by the torque demanded by the
starter-generator 130, and the current through the LPDM 160 may be
determined by the pressure demand on the LPDM 160.
FIG. 5 illustrates a method 300 of controlling a cold start event
for a gas turbine engine without using a gearbox, according to an
embodiment of the present invention. The method 300 may first
provide for sensing the bulk oil temperature in step 310. If the
bulk oil temperature is below a pre-determined threshold
temperature, then method 300 may proceed with a step 320 of
activating a starter/pump controller, to cause the routing of power
from an energy source to the starter-generator 130 in step 330,
until a net positive torque is created in starter-generator 130.
While the power is routed to the starter-generator 130, power to an
accessory drive motor, such as the LPDM 160 may be limited. When a
positive torque is created by the starter-generator 130, then
additional power may be routed to an accessory drive motor, such as
a LPDM 160.
Further, as illustrated in FIG. 6, computer readable media 500 may
be operable with the method and apparatus of the present invention
for uses such as memory, control of the sensor-controller 110 and
the starter/pump controller 120, displaying the power input and
mainshaft speed, calculations, or backup. The computer readable
media 500 operably connected to a first controlling computer
program 510 to initiate a starter/pump controller 120 if a bulk oil
temperature is less than a pre-determined value. The computer
readable media 500 may also be operably connected to a second
controlling computer program 520 to control the routing of power
from an energy source 100 to a starter-generator 130. The second
controlling computer program 520 simultaneously limiting power to
an accessory drive motor, such as an LPDM 160, while the
starter-generator 130 is producing negative net torque.
Further, the computer readable media 500 may be operable for
determining, storing, writing, reading, or recording of information
generated during the first or second controlling computer
program.
FIG. 7 illustrates another exemplary embodiment. An energy source
100, such as a battery is operably connected to the FADEC 122. The
FADEC 122 is operably connected to two sensors, a turbomachine
supply system oil pressure sensor 22, and an oil temperature sensor
20, either or both of which may trigger FADEC 122 power management.
The FADEC 122 is capable of controlling accessories such as the
starter-generator 139, a fuel pump drive motor 180, or a LPDM 160.
The fuel pump drive motor 180 is shown being connected to the fuel
pump 182. The LPDM 160 is shown being connected to the LPDM pump
170. Here, if the oil temperature is above a threshold (warm)
temperature; or if the pressure is above a threshold value, the
FADEC 122 will initiate normal warm start mechanization logic. The
FADEC 122 will evaluate the oil temperature sensor signal
immediately prior to start initiation. If the oil temperature or
pressure is below the respective threshold temperature, the cold
start mechanization logic of the present invention, as described
above, is initiated. The FADEC 122 may look at the turbo machine
inlet lubrication system pressure signal and utilize a unique cold
start supply system closed loop oil pressure schedule to provide
adequate cooling and lubrication flow for oil cooled components
(i.e. LPDM 160) within the turbomachine 145 while the turbomachine
transitions from cold start conditions to steady state lubrication
system command and control.
In one exemplary embodiment of the present invention, if the oil
temperature is cold, the FADEC 122 will control and distribute
electrical power to the starter-generator 130, the electric motor
driven fuel pump 182, and the electric motor driven lubrication
pump 170 to minimize the total airframe energy required for a
successful turbomachine 145 cold start. The electric power transfer
to, for example, the LPDM 160, will be reduced early in the start
sequence prioritizing power transfer to, for example, the
starter-generator 130 and electric motor driven fuel pump 180.
Additional electric power may be transferred to the lubrication
pump electric motor when the turbomachine 145 has reached a
self-sustaining speed (430 in FIG. 3). Thereby producing net output
torque and the starter-generator can transition into a "generate"
mode, to produce excess electrical power, which can be routed to,
for example, the LPDM 160 to accelerate the pump 170 and circulate
cooling oil to turbomachine 145 wetted components.
As illustrated in FIG. 8, in a further exemplary embodiment, the
starter-generator 130 transition to "generate" mode may be sensed
via a turbomachine rotor 140 position or speed sensor (not
shown).
In further exemplary embodiments of the present invention, rotor or
shaft 140 position sensors (not shown) may be utilized to initiate
the cold start sequence of the present invention.
It should be understood, of course, that the foregoing relates to
exemplary embodiments of the invention and that modifications may
be made without departing from the spirit and scope of the
invention as set forth in the following claims.
* * * * *